Effect of Severe Fever With Thrombocytopenia Syndrome Virus Genotype on Disease Severity, Viral Load, and Cytokines in South Korea.

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease caused by Bandavirus dabieense (SFTS virus [SFTSV]). Recently, at least 6 different genotypes of SFTSV have been identified, with genotypes A, D, and F dominant in China and B dominant in Japan and Korea. This study investigated the effect of SFTSV genotypes circulating in South Korea on disease severity, viral load, and cytokine profile. Methods: We prospectively enrolled 70 patients with SFTS from July 2015 to June 2022. Serial plasma samples were obtained during hospitalization and analyzed. Viral load was measured by real-time reverse-transcription polymerase chain reaction. Partial sequences of the viral genome were analyzed for genotyping. Plasma concentrations of 17 cytokines were measured by multiplex-bead immunoassay. Results: Of 70 samples, 51 could be genotyped. Genotype B was predominant (80.4%) and other genotypes were uncommon. Intensive care unit admission rates (51.2% vs 50.0%) and mortality rates (26.8% vs 40.0%) did not show any significant differences between genotype B and non-B genotypes. The initial viral load did not show any significant differences (3.59 vs 3.64 log copies/µL), whereas viral load measured at hospital day 3-4 tended to be higher in genotype B than non-B genotypes (3.83 vs 1.83 log copies/µL, P = .07). Additionally, the plasma concentrations of interferon-α, interleukin 10, and interferon-γ-induced protein 10, which are closely related to mortality in cases of SFTS, did not show any significant differences. Conclusions: SFTSV genotype B was the prevalent genotype in South Korea, with no genotype-specific difference in clinical outcomes, initial viral load, or cytokine profiles.

Viral, Immunologic, and Laboratory Parameters in Patients With and Without Post-Acute Sequelae of SARS-CoV-2 Infection (PASC).

BACKGROUND: The pathophysiological mechanisms underlying the post-acute sequelae of severe acute respiratory syndrome coronavirus 2 infection (PASC) are not well understood. Our study aimed to investigate various aspects of theses mechanisms, including viral persistence, immunological responses, and laboratory parameters in patients with and without PASC. METHODS: We prospectively enrolled adults aged ≥ 18 years diagnosed with coronavirus disease 2019 (COVID-19) between August 2022 and July 2023. Blood samples were collected at three time-points: within one month of diagnosis (acute phase) and at 1 month, and 3 months post-diagnosis. Following a recent well-designed definition of PASC, PASC patients were defined as those with a questionnaire-based PASC score ≥ 12 persisting for at least 4 weeks after the initial COVID-19 diagnosis. RESULTS: Of 57 eligible COVID-19 patients, 29 (51%) had PASC, and 28 (49%) did not. The PASC group had significantly higher nucleocapsid protein (NP) antigenemia 3 months after COVID-19 diagnosis (P = 0.022). Furthermore, several cytokines, including IL-2, IL-17A, VEGF, RANTES, sCD40L, IP-10, I-TAC, and granzyme A, were markedly elevated in the PASC group 1 and/or 3 month(s) after COVID-19 diagnosis. In contrast, the median values of several serological markers, including thyroid markers, autoimmune indicators, and stress-related hormones, were within the normal range. CONCLUSION: Levels of NP antigen and of various cytokines involved in immune responses become significantly elevated over time after COVID-19 diagnosis in PASC patients compared to non-PASC patients. This suggests that PASC is associated with prolonged immune dysregulation resulting from heightened antigenic stimulation.

The Association Between Antibody Responses and Prolonged Viable Severe Acute Respiratory Syndrome Coronavirus 2 Shedding in Immunocompromised Patients: A Prospective Cohort Study.

Immunocompromised patients with coronavirus disease 2019 were prospectively enrolled from March to November 2022 to understand the association between antibody responses and severe acute respiratory syndrome coronavirus 2 shedding. A total of 62 patients were analyzed, and the results indicated a faster decline in genomic and subgenomic viral RNA in patients with higher neutralizing and S1-specific immunoglobulin G (IgG) antibodies (both P < .001). Notably, high neutralizing antibody levels were associated with a significantly faster decrease in viable virus cultures (P = .04). Our observations suggest the role of neutralizing antibodies in prolonged virus shedding in immunocompromised patients, highlighting the potential benefits of enhancing their humoral immune response through vaccination or monoclonal antibody treatments.

Virological characteristics and the rapid antigen test as deisolation criteria in immunocompromised patients with COVID-19: A prospective cohort study.

There are limited data supporting current Centers for Disease Control and Prevention guidelines for the isolation period in moderate to severely immunocompromised patients with coronavirus disease 2019 (COVID-19). Adult COVID-19 patients who underwent solid organ transplantation (SOT) or received active chemotherapy against hematologic malignancy were enrolled and weekly respiratory samples were collected. Samples with positive genomic real-time polymerase chain reaction results underwent virus culture and rapid antigen testing (RAT). A total of 65 patients (40 with hematologic malignancy and 25 SOT) were enrolled. The median duration of viable virus shedding was 4 weeks (interquartile range: 3-7). Multivariable analysis revealed that B-cell depletion (hazard ratio [HR]: 4.76) was associated with prolonged viral shedding, and COVID-19 vaccination (≥3 doses) was negatively associated with prolonged viral shedding (HR: 0.22). The sensitivity, specificity, positive predictive value, and negative predictive value of RAT for viable virus shedding were 79%, 76%, 74%, and 81%, respectively. The negative predictive value of RAT was only 48% (95% confidence interval [CI]: 33-65) in the samples from those with symptom onset ≤20 days, but it was as high as 92% (95% CI: 85-96) in the samples from those with symptom onset >20 days. About half of immunocompromised COVID-19 patients shed viable virus for ≥4 weeks from the diagnosis, and virus shedding was prolonged especially in unvaccinated patients with B-cell-depleting therapy treatment. RAT beyond 20 days in immunocompromised patients had a relatively high negative predictive value for viable virus shedding.